`parallel/test-http2-close-while-writing` is flaky

[lpinca]

Test

test-http2-close-while-writing

Platform

macOS x64

Console output

---
duration_ms: 120080.257
exitcode: -15
severity: fail
stack: timeout
...

Build links

• https://ci.nodejs.org/job/node-test-commit-osx/64920/nodes=osx13-x64/testReport/junit/(root)/parallel/test_http2_close_while_writing/
• https://ci.nodejs.org/job/node-test-commit-osx/64990/nodes=osx13-x64/testReport/junit/(root)/parallel/test_http2_close_while_writing/

Additional information

I can reproduce the issue locally via

$ python3 tools/test.py --repeat=10000 parallel/test-http2-close-while-writing

$ lldb -p 79156
(lldb) process attach --pid 79156
Process 79156 stopped
* thread #1, name = 'MainThread', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
 frame #0: 0x00007ff80b21281e libsystem_kernel.dylib`kevent + 10
libsystem_kernel.dylib`kevent:
-> 0x7ff80b21281e <+10>: jae 0x7ff80b212828 ; <+20>
 0x7ff80b212820 <+12>: movq %rax, %rdi
 0x7ff80b212823 <+15>: jmp 0x7ff80b20e2a2 ; cerror_nocancel
 0x7ff80b212828 <+20>: retq 
Target 0: (node) stopped.
Executable binary set to "/Users/luigi/code/node/out/Release/node".
Architecture set to: x86_64-apple-macosx-.
(lldb) bt
* thread #1, name = 'MainThread', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
 * frame #0: 0x00007ff80b21281e libsystem_kernel.dylib`kevent + 10
 frame #1: 0x000000010543d4ec node`uv__io_poll(loop=<unavailable>, timeout=<unavailable>) at kqueue.c:286:12 [opt]
 frame #2: 0x0000000105429280 node`uv_run(loop=0x0000000109b4d530, mode=UV_RUN_DEFAULT) at core.c:460:5 [opt]
 frame #3: 0x00000001044e6663 node`node::SpinEventLoopInternal(env=0x00007f80ee009600) at embed_helpers.cc:41:7 [opt]
 frame #4: 0x00000001046072bd node`node::NodeMainInstance::Run() [inlined] node::NodeMainInstance::Run(this=<unavailable>, exit_code=<unavailable>, env=0x00007f80ee009600) at node_main_instance.cc:110:9 [opt]
 frame #5: 0x0000000104607229 node`node::NodeMainInstance::Run(this=<unavailable>) at node_main_instance.cc:99:3 [opt]
 frame #6: 0x0000000104591aef node`node::Start(int, char**) [inlined] node::StartInternal(argc=<unavailable>, argv=<unavailable>) at node.cc:1545:24 [opt]
 frame #7: 0x0000000104591aa4 node`node::Start(argc=<unavailable>, argv=<unavailable>) at node.cc:1552:27 [opt]
 frame #8: 0x00007ff80aeab530 dyld`start + 3056

[lpinca]

This callback

node/test/parallel/test-http2-close-while-writing.js

Line 40 in 264cad7

client_stream.on('close', common.mustCall(() => {

is called when the test times out.

[lpinca]

I don't think the original intention was to call stream.write(Buffer.alloc(1)) for each received chunk, and the following patch fixes the issue

diff --git a/test/parallel/test-http2-close-while-writing.js b/test/parallel/test-http2-close-while-writing.js
index d8537c31b00..231bf712d40 100644
--- a/test/parallel/test-http2-close-while-writing.js
+++ b/test/parallel/test-http2-close-while-writing.js
@@ -23,8 +23,8 @@ let client_stream;
 
 server.on('session', common.mustCall(function(session) {
 session.on('stream', common.mustCall(function(stream) {
- stream.resume();
- stream.on('data', function() {
+ stream.once('data', function() {
+ this.resume();
 this.write(Buffer.alloc(1));
 process.nextTick(() => client_stream.destroy());
 });

However it is not clear to me why the stream sometimes hangs. The reason for the hang/timeout is that this callback

node/lib/internal/http2/core.js

Lines 2192 to 2196 in 6710c00

	const writeCallback = (err) => {
	waitingForWriteCallback = false;
	writeCallbackErr = err;
	done();
	};

is not called.

I'm not opening a PR with the patch because it would hide the bug.

cc: @nodejs/http2

[github-actions]

This issue has been marked as stale due to 210 days of inactivity.
It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.

[lpinca]

It is still relevant.